Magnesium base alloy



atented Nov. 12, 1940 sures PATENT 0001c MAGNESIUM BASE ALLOY No Drawing. Application November 13, 1939, Serial No. 304,136

30laims.

The invention relates to magnesium base alloys. It more particularly concerns alloys of this nature having a high degree of iormability coupled with other improved physical properties, such as improved strength characteristics.

Magnesium alloys are enjoying increasing use in the structural and mechanical arts where a light weight metal is highly desirable, such as for use in making large castings, forgings, and

the like. However, the use of these alloys in the rolled form to make sheet metal articles requiring forming operations has not progressed as rapidly due to the fact that in general alloys of good formability, permitting relatively sharp bends to be made without the article developing external cracks, usually have inferior characteristics as regards their tensile and yield strengths.

It is, accordingly, the principal object of the invention to provide a magnesium base alloy which may be made into rolled sheet or the like, possessing a suflicient degree of ductility or formability to be sharply bent, drawn, or otherwise shaped, while having improved tensile and yield strengths.

Other objects and advantages will be ap arent as the description of the invention proceeds.

My invention resides in the discovery that a magnesium base alloy composed of from 0.3 to

coupled with high tensile and yield strengths, is found in alloys containing from 0.5 to 5 per 'cent of silver, 0.1 to 0.3 percent of calcium, 5 to 10 per cent of cadmium, 1.5 to 2.5 per cent of manganese, and from 0.5 to 5 per cent of zinc. 5

The specific proportions of each alloying metal and the total amount of addedalloying metals to be employed depends upon the use for which the alloy is intended. general it is preferable to employ an alloy containing more than about 75 m per cent of magnesium and'less than about 25 per cent of the total added alloying metals. For example, in alloys where a high ductility or ionmability is of prime importance, the total added alloying metals should not exceed about 15 15 per cent, while in those instances where high yield and tensile strengths are desired, especially in the cold-rolled state, higher percentages of the alloying metals should be employed.

The following table, which lists some of the 90 properties of rolled sheet metal made from my new alloys, as well as the properties of the related parentalloys in similar form, illustrates the improvement in yield and tensile strengths, and ductility or iormability of the new alloys over a hat of the closely related alloys. In, the table, the per cent elongation represents the ductility or iormability oi the alloys.

3 Nominal composition in nt 80 Annealed 001011011011 c c. M m an M .0 01... mas... o n n o 11 ng a g lb|.l0q.in. lba/aq'. in. 2 0110s lbs./sq.in lbsJcq. y I 85 0.0 0.0 0.0 1 000 30.000 10 40,000 3 000 1.0 0.0 00 1.1 @000 01,000 10 30,000 film 0.0 0.0 4.0 1.4 4.0 31,000 40,000 14 40,000 02,000 0.0 1.0 1.1 0.0 20,000 00,000 10 42,000 48,0(D 1.0 0.0 2.1 0.0 20,000 00,000 10 40,000 40,000 02 2-: H a: as as 0 0.1 013 010 1.0 00,000 aaooo 10 41,000 40,000 m 0.0 0.0 0.0 20 0.0 00,000 41,000 11 44,000 01,000 0.2 0.0 1.0 0.0 2,000 40,000 10 41,000 02,000 0.0 0.0 40 1.0 00 31,000 40,000 10 40,000 04,000

10 per cent of silver, 1 to 15 per cent of cadmium. 0.05 to 1.0 per cent of calcium, 0.1 to 3 per cent of manganese, and from 0.1 to 10 per cent of zinc, the balance being substantially all magnesium, is endowed with the afore-mentioned properties. While the property of satisfactory tormability or ductility, coupled with high tensile and yield strengths, is manifest over the entire range of composition indicated, I have found that in general the preferred combination oi properties.

such as good ductility for forming operations The properties-listed in the above table under 45 the section headed by the term annealed were obtained by first rolling the alloys at a temperature between about 500 to 600 F., and thereafter annealing them at various temperatures through a temperature range of from 400 to 800 .50,

which had been hot rolled at a temperature of from 500 to 600 F. to additional rolling in the cold state to bring about a total reduction of from 2 to per cent. The properties selected for the table were those of the cold rolled specimens which showed the greatest tensile and yield strengths, while having at least a 1 per cent elongation in 2 inches.

By comparison of the properties listed in the above table, it will be observed that the combined properties of my new polynary alloys are superior to those of the parent alloys having somewhat similar percentages of alloying ingredients. For example, it will be noted that the per cent elongation, which serves as a measure of the ductility, is satisfactorily high, while the yield strength and tensile strength in both the annealed and in the cold rolled state show marked improvement over that of the related alloys. Similarly other portions of the composition range show improved properties over those of the related alloys.

While the new alloy is most useful in wrought form, such as sheets, due to its formability characteristics, it may also be suitably used in making castings, forgings, extruded forms, and the like. It is further pointed out that my new alloy is amenable to solution and precipitation heat treatments, which, accordingly, modify its properties.

The new alloy may be compounded in any of the ways known to the art, such as by adding the alloying ingredients to the molten magnesium under a suitable flux. The flux should be substantially free irom magnesium chloride if the calcium content of the alloy is to be above 0.3 per cent. In those instances where an alloy is to be compounded containing less than 0.3 per cent of calcium, the presence of a small amount of magnesium chloride in the flux does not exert an undue deleterious effect, but in this case it is usually preferable to add the calcium last and without too much stirring, in order that the loss 01' calcium into the flux will be prevented.

I claim:

1. A magnesium base alloy containing from 0.3 to 10 per cent of silver, 0.05 to 1 per cent 01' calcium, 1 to per cent 01' cadmium, 0.1 to 3 per cent of manganese, and from 0.1 to 10 per cent of zinc, the balance being magnesium.

2. A magnesium base alloy containing from 1 to 8 per cent of silver, 0.1 to 0.8 per cent of calcium, 1 to 12 per cent of cadmium, 0.1 to 3 per cent of manganese, and from 0.1 to 10 per cent of zinc, the balance being magnesium.

3. A magnesium base alloy containing from 0.5 to 5 per cent of silver, 0.1 to 0.3 per cent of calcium, 5 to 10 per cent of cadmium, 1.5 to 2.5 per cent of manganese, and from 0.5 to 5 per cent of zinc, the balance being magnesium.

JOHN c. MCDONALD. 

